Problems about electronics inside the guitar

Discussion in 'PTC - PRS Tech Center' started by s2000115, Jul 2, 2015.

  1. s2000115

    s2000115 New Member

    Joined:
    Jul 1, 2015
    Messages:
    1
    Likes Received:
    0
    First of all, I know nothing about wiring of guitar and I have some questions about wiring.
    One day I took my second hand custom 24 to a guitar tech because of the sound of it was muffled when the volume pot turned down.
    The guitar tech told me that the previous owner changed the volume pot to a wrong pot and that's why it sounds muffled.
    He also helped me to re-wire all of the wires inside the cavity as he said it is quite messy inside.
    Recently, I found than if I switch it to bridge pickup and touching the metal parts of the guitar, noises will come out from the amp.
    I google it and found that it was the grounding issue but I don't know how to fix it as the wire inside is quite complicated to me.
    I also found that the capacitor was connected to a wrong position on the volume pot according to the PRS official wiring diagram.
    So my questions is: Would the grounding issue and the wrong welded capacitor affecting the tone of guitar?
    Here are some pictures of the cavity:
    [​IMG]

    [​IMG]

    [​IMG]
    Capacitor connected to the wrong pin on the volume pot, it should be welded on the middle pin.
     
  2. Goldfixer

    Goldfixer Is it football season yet?

    Joined:
    Apr 26, 2012
    Messages:
    141
    Likes Received:
    66
    wiring diagrams for PRS guitars are available on their web site
     
  3. John Beef

    John Beef Opaque

    Joined:
    Apr 27, 2012
    Messages:
    2,807
    Likes Received:
    740
    It's hard to tell in the pics because the wiring is pretty messy. I will try to offer my input.

    There is a ground wire leading from the back of the volume pot to the claw of the trem. You don't show how it's connected on the trem but the soldering is poor on the back of the volume pot. You need a hotter soldering iron to really heat the back of the pot up so you get a good bond there. That one looks like it could be a cold solder joint.

    Another source of grounding issues might be the way the pickups and output to the jack are all stacked on one another. Electrically that seems like it should work but I wouldn't do it that way.

    Also, I don't see a problem with the cap. You can wire it up the way it's wired; in fact that's how I prefer it. the other way (middle lug of the volume pot) is called 50s wiring and makes the tone control behave a little differently. that's a personal preference thing.

    I can tell you the pickups should be out of phase in the middle position the way it's currently wired. Because PRS 3 wire pickups are made to work with the blade and rotary switches, when you put them in a guitar like this, the colors are reversed for hot and ground. It looks like you have black as the hot for both, and it should be black for one and white for the other.

    Hope this helps.
     
  4. wardog

    wardog What the gravy and cheese!!!!

    Joined:
    Mar 30, 2013
    Messages:
    1,185
    Likes Received:
    81
    I agree on the ground leads for the pickup. I good ground layout will have the input Jack braided sleeve grounded to the volume pot and then everything grounded to the VOLUME pot. The way it is done on your guitar can lead to issues with double grounding or over grounding if that makes sense. I can't remember the exact effect or term but I read it when I installed my acoustic piezo in my electric guitar.

    I also agree on the fact the guitar tech was not familiar with PRS pickups. The red/white/black lead pickups magnetics are not placed the same. The neck pickup's magnetic is flipped. The low volume your hearing is due to the pickups going out of phase.

    you can achieve the correct control setup with your current layout by using the correct wiring schematic on the support page of the PRS site. I would print it and have a good guitar tech redo the wiring to that schematic.

    Okay here is the link
    http://www.prsguitars.com/csc/schematics/schem08/custom3waytoggle.pdf

    Oh and welcome to the Club!!! Let's see some pics of the whole guitar in a thread in the electric section!!!
     
    #4 wardog, Jul 3, 2015
    Last edited: Jul 3, 2015
  5. Mixstar

    Mixstar Just too tired . . .

    Joined:
    Mar 17, 2015
    Messages:
    690
    Likes Received:
    148
    When grounding you have to be very careful about causing return/earth loops. All screens and mains earths interconnect and because any cable has a finite resistance there's a real danger that interference signals will cause current to flow in the cable screens (you can actually see this if you test it with an oscilloscope) resulting in audible signal contamination. As an electrical engineer it's easy for me to say I know but if it were me I'd de-solder the lot so you have a clean canvass and start again. As previously mentioned, wiring diagrams are available so I would wire it exactly as the diagram shows it should be and you should be good to go. Other tips, make sure your soldering iron is hot enough, always tin surfaces that need to take solder including the wires before soldering. Good soldering practice is 90% of getting a good clean sound. Any badly soldered joints can add noise, capacitance and resistance to the circuit. Remember, the first radios tuned using a bad connection (a semiconductor similar to a diode basically) so if you start adding bad connections you could end up having an FM radio station playing through your amp.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice